Workflow for creating Chamfers


Fairly new to Sketchup. (2 months.) I am more accustomed to parametric modeling CAD Software, (Solidworks, Autodesk Inventor) but am getting the hang of SU/LO. I haven’t dived into plugins yet, I’m trying to get a grasp for the process to be able to do it with or without them.

I have a project that will be made out of Aluminum Composite Material/ACM and V-groove bit to fold into a box and skin. The odd angles of it made me decide to lay out the components flat in a column, to be able to edit a component separate from the assembly at odd angles so I don’t push/pull or move at a wrong angle.

I am trying to figure out workflow for making chamfers on these parts to represent the V-Grooves and then be able to make the flat .dxf file for router. My progress is attached. Blue & Red outlines are the .dxf files I exported for each piece. This will work for now, but I’d like to understand it better to clean up my models in the future.

*The main question is, How do I go about getting consistent Chamfers on parts? If you look in bottom left, I created the 2 processes with guidelines I went about making them. But then if you look under UNFOLDED ACM column at end, if you zoom into where V-Grooves should meet, you’ll see they didn’t end up square/consistent. Maybe I messed something up along the way with MOVE not being exact? (I always snap to an axis (red here) when push/pulling the chamfers)

*Also, How might you go about the miter cut and chamfered pieces. Think flaps of the outer shell components.

Thank you.


There’s no need to model the panels with thickness to merely find the lengths and miter angles necessary to fabricate the parts.

Simply model the exterior Faces only.
This (free) plugin will yield the miter angles with one click on an Edge of adjacent Faces.

Angle Between Planes v1.0 — SketchUp plugin by Clark Bremner

You’ll find more info in this topic…

I understand that I don’t need 3D geometry for the task, however it’d be nice to understand how to actually do it more effectively and accurately.

Looking over my model, I noticed there would be a corner that would be 1/64" or so off from being perfectly co planar. So I am thinking maybe it’s just me being sloppy and not realizing it?

When you draw a shape or move/push/pull etc. and the line turns red, does it always move 100% in the red direction? Or do I have to actually lock it in the red direction with shift or an arrow to make it bold red for it to be 100% locked along that one axis? Am I actually drawing things on a small angle and not realizing it?

Thank you.

It depends on what you mean by “the line turns red”. If you mean that you see a red inference line as you move the cursor before you click to finish an edge, the edge should be accurately along red. It will also be accurate if you lock the inference using the shift key or right arrow.

But if you mean that you have “color by axis” turned on and are seeing the edge turn red after you draw it, that technique is not reliable. Color by axis has a tolerance and will color edges that are actually slightly out of alignment. It is really only useful as a coarse indicator.

I was referring to how you first described it. If I pull in the general red direction, its black and then when I actually hit red axis direction it turns red. Then to lock it with shift or arrow it turns a bold red. It sounds like you confirmed either of those (red inference, or red bold/locked inference) are accurately along that red axis.

I’m not positive what color by axis is yet.

First, up the Units Precision settings.
You can’t model or measure precisely using settings like those found in the model you shared.


That’s typically what I have been modeling in, but when I was digging deeper to try and understand I made the display precision finer. Also downloaded Utilities Tools extension to get coordinates of vertices to see if what I drew was all square.

Regardless of those units, I can draw in finer units if I am typing them correct? Say I drew something off a centerline and typed in something to 1/32" precision to the right and left to make 1/16" it will be 1/32" precision off that line, but say ~1/16" when tape measured since it rounds up for the display precision.

This is kind of what got me to realize it. When I unfolded my panels I was measuring a distance of ~23.125" and not =23.125", so in my mind when all the panels were all drawn to round numbers (1/8") it should have added up to exactly 23.125" not ~23.125".

Am I just thinking about this all wrong?

Side note: I used to work in a sheet metal shop where the guy on the press brake who’s been doing it longer than I have been alive would point out if I was .015" off. Maybe I’m scarred from that.

The Query tool is pretty handy for sorting accuracy issues.
But, the Measurement Units it displays are the current Units and Precision setting.
A tilde (one of these things ~) in front of a number is rather worthless in terms of measuring with precision.

The old boy at the press brake was trying to teach you something.
You can’t achieve precision using a red plastic ruler graduated in 1/16’s

Learn to be comfortable working in decimal units.
Most of world does already, whether in inch or metric.

Decimal Equivalents Chart.pdf (878.9 KB)

Being a tapered box, the beveled edges of the panels will not be exactly 45°
However, in working with the model, it seems the beveled edges of the panels are all 45°
Is that your intent, or should they be off angles?

It’s not clear how you intend to cut these off angle miters on the CNC
Is it a miter-fold v-cut, where you cut away the back face and core, leaving the face?

Your belittling over units has been oh so helpful. Thanks a lot. I work/think in decimal… I’m not typing 5/16, I’m typing .3125. If I were to put decimal units on shop drawings to a cabinet making shop, I’d be crucified. The Tilda actually is useful because if it appears, I know to go back and check myself. There’s more than one way to skin a cat George. Just because you find something worthless, doesn’t mean it’s worthless to the entire population.

All I was asking was, how do I make the shapes in SU more accurately. It’s 3 simple steps in Inventor/Solidworks. (Could be 2 really) The actual question has never been addressed here.

I’ll just figure it out on my own. Thanks.

i use comps/groups with hidden edges when I need both .dxf out and a 3d image…

ProE has one of the best metal folding plugins, but it cost a bit and is bespoke PC only…


Ignoring the sarcasm and mixed messages, here’s a way to model the off angles.

Perfect Miters.skp (38.5 KB)

Not in the AWI Premium certified shop where I served many years.
Glenn Rieder, Inc.

For your interest.

Thank you.

I think we may think in the opposite direction. You take the finished assembly and back out the individual parts, I think build raw good individual parts and then assemble into final assembly.

In regards to the model you shared. I follow what you are doing other than ‘Including interior faces’

*When you say Parent, are you referring to the wireframe first model, or the one with the outer faces second one?
*How do you include those interior faces and then include them when you move+copy? I can only select the 4 visible faces and then would have to draw in the lines to complete the panel sides 5&6?
*Also do you use groups/components at all for something like this, or did you just not include them just to demonstrate?

Thank you.

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What I termed the Parent model is the fully fleshed out second one.
No grouping involved. It’s all one mass of stuck together raw geometry.

The key to moving a copy of one entire side away from the mass is in selecting only what you want.
In building the demo model, I set the camera to top view and parallel projection.

Dragging a L-R selection box selects only what the selection window encompasses.
That made selecting just one entire side and nothing else pretty straightforward.
One can always erase any extra geometry if the copy inadvertently brings along more than needed.

Creating a closed loop of coplanar Edges automatically creates a Face.
The interior Faces at the corners appeared automatically when using the Line tool to connect the respective top and bottom corners.